Some times you may not want the Browser Link that appears in the browser source code when you run the application in Browser from Visual studio.
To do this you can keep following appSettings in the web.config file of your application.
<add key="vs:EnableBrowserLink" value="false" />
Browser link helps in real time debugging and development of CSS used in the application ie. you an change the .css file and the application running in the browser changes in real time without refreshing.
Regards,
Sheo Narayan
http://www.dotnetfunda.com